1. Field of the Invention
This invention relates to a digital frequency generator which includes first and second clock generators and a frequency adder stage.
2. Description of the Related Art
U.S. Pat. No. 4,308,619 discloses a phase control stage comprising an adder circuit for two clock signals having two different frequencies. The two clock signals to be added up are applied to a D flip-flop and a NOR gate. Such a circuit arrangement ensures that even with partly or completely overlapping pulses of the two clock signals to be added up the sum of the two clock signals is formed exactly.
Averaged over various periods of the low-frequency clock signal, the exact sum of the frequencies of the two clock signals is obtained in this manner. Within a period of the low-frequency clock signal the distribution of the clock edges over the period of this clock signal is inhomogeneous.